Question

Suggest a product of the following reaction. HI is a very strong acid. $$ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{3}+2 \mathrm{HI} \longrightarrow $$

Short answer

Answer: The products of this reaction are iodoethane (CH3CH2I) and ethanol (CH3CH2OH).

Step-by-step solution

Identify the reactants and the reaction type

The reactants are CH3CH2OCH2CH3 (an ether) and HI (a strong acid). The reaction is an acid-catalyzed cleavage of the ether.

Determine the cleavage site in the ether

In the ether molecule, CH3CH2OCH2CH3, the bond that could be broken is between the oxygen atom and one of the carbon atoms. Since HI will react with the least substituted carbon (primary), oxygen will break the bond with CH2CH3.

Perform the reaction and create the product

When the bond between the oxygen and the CH2CH3 breaks, a proton from the HI will be attached to the oxygen atom, and iodine will take the place of the oxygen in the CH2CH3 group. The products thus formed will be CH3CH2OH (ethanol) and CH3CH2I (iodoethane). The reaction can be described as: $$ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{3}+2 \mathrm{HI} \longrightarrow \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{I} + \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH} $$ Overall, the reaction between CH3CH2OCH2CH3 and 2HI produces iodoethane (CH3CH2I) and ethanol (CH3CH2OH).

Key concepts

Organic Chemistry Reactions

In organic chemistry, reactions are the heart of synthesis and structural manipulation of organic molecules. They are classified based on the type of transformation the organic molecule undergoes, like substitutions, additions, eliminations, and rearrangements. Acid-catalyzed cleavage of ethers such as in the given exercise where diethyl ether reacts with hydrogen iodide (HI) is a classic example of a substitution reaction.

An acid-catalyzed reaction generally involves a proton (H⁺) from an acid adding to a molecule, making it more electrophilic and susceptible to nucleophilic attack. This reaction type is pivotal in creating a wide array of substances, including pharmaceuticals, plastics, and polymers, thus being essential knowledge for students and professional chemists alike.

Cleavage of Ethers

Ethers, characterized by an oxygen atom connected to two alkyl or aryl groups, can be selectively cleaved or broken apart in the presence of strong acids. The cleavage of ethers is notable for its predictability and usefulness in synthesis.

In acid-catalyzed cleavage, the ether oxygen first gets protonated, increasing its electrophilicity. Then, a nucleophile, such as iodide ion (I^-) from HI, attacks the carbon atom bonded to the oxygen. This step is followed by the departure of the alkyl group, resulting in the formation of an alcohol and an alkyl halide, as presented in the example problem.

Reaction Mechanisms

Understanding the reaction mechanism gives insight into the step-by-step process by which chemical reactions occur. It includes the breaking and forming of bonds, the rearrangement of atoms, and the intermediate states of the reactants. For the cleavage of ethers, the mechanism involves the initial protonation of the ether oxygen, rendering it a better leaving group, followed by the nucleophilic attack and bond cleavage, leading to product formation.

Visualizing these mechanisms helps students to predict reaction outcomes and manipulate conditions to steer the reaction. Moreover, it aids in troubleshooting when reactions do not proceed as planned and in designing novel synthetic pathways.

Organic Chemistry Synthesis

Synthesis in organic chemistry is the art of building complex organic compounds from simpler ones through a series of chemical reactions. Synthesizing molecules involves understanding both the functional group transformations and the mechanisms of individual steps.

Acid-catalyzed cleavage of ethers is often utilized to generate alcohol and alkyl halide products, which are valuable intermediates in the synthesis of more complex molecules. Considering reactant availability, reaction conditions, and the desired product's yield and purity are key aspects of successful organic synthesis, prominently featured in academic curricula and industry research. Hence, mastering such reactions and their mechanisms is crucial for aspiring chemists.